Wooden culvert construction



Nov. 23, 1943. SHAFER 2,334,846

WOODEN CULVERT CONSTRUCTION Filed July 2, 1942 4+1 q BY (zllm/q'wa 'i) FIG.]Z. ATTORNEYS.

Patented Nov. 23, 1943 WOODEN cunvnn'r CONSTRUCTION- George E. Shafer, Middletown, Ohio, assignor to The American Rolling Mill Company, Middletown, Ohio, a. corporation oi Ohio Application July 2, 1942, Serial No. 449,432

16Claims.

Experience has shown that there is a field of utility for a wooden structure for culverts or conduits, where a strength factor at least equal to the strength factor of corrugated metal culvert and pipe of the gauges used for the same diameters, can be obtained, at costs not substantially greater than the costs of the equivalentmetal structures. A fundamental object of my invention is the provision of such wooden structures.

It has been found that exceedingly strong wooden structures can be formed of polygonal cross section having sides greater than four in number, by building up said structures from individual wooden pieces where the grain direction of the pieces is transverse to the axis of the culvert or conduit, and where the pieces at their ends have suitable interengagement. The pieces are disposed at an angle to each other substantially less than a straight angle, and substantially greater than a right angle, and th nature of the interengagement of the pieces is such that it tends strongly to resist an increase of angularity between the said pieces.

It has been found'that wooden structures so characterized have sufiicient elasticity and deformability to permit them to act under dead and live loads like the familiar circumferentially corrugated metallic culvert of commerce. In other words, such culverts, under top load when in a fill, are capable of deforming so as to seek side support,.or until the side, top and bottom forces on the culvert are substantially equalized. When these forces are equalized, there is a great increase in the ultimate strength of the culvert or conduit. It is well known in the testing and operation of corrugated metallic culverts that the amount of load which can be sustained by the culvert when it is given side support, or when side support is provided by a slight distortion of the culvert, is several times the load which it can sustain without side support. It is an object of the present invention to provide a wooden structure in which the same thing is true.

It is an object of my invention to provide a wooden structure of the class referred to, in which the several parts or elements ar readily assembled, and when assembled, provide either integral and self-sustaining culverts or conduits as such, or integral and self-sustaining ring-like structures which may be joined together to form a culvert or conduit.

It is an object of my invention to provide a structure in which the individual elements, when in engagement, are capable of maintaining their engagement -without the use of dowels or any other extraneous fastening means.

It is an object of my invention to provide a structure wherein the individual elements not only have such interengagement as will strongly resist any increase of the angularity between them,

but in which they are also enabled to bear against each other like the stones in a stone arch, so as to avoid or minimize shearing strains in the individual members.

It is also an object of my invention to provide a structure wherein, if desired, the individual elements may be so interenga ed as not only to form ring shaped structures transversel of the culvert or conduit, but also so as to combine these structures together in the direction of the length of the culvert.

These and other objects of my invention which will be set forth hereinafter, or will be apparent to one skilled in the art upon reading these specifications, I accomplish in those structures and arrangements of parts and in the Procedures of which I shall now disclose certain exemplary embodiments. I

Reference is had to the drawing, wherein:

Figure 1 is a perspective view of one of my individual members or elements, showing the side which is to be disposed toward the outside of the completed structure.

Fig. 2 is a companion perspective view showing the other side of the same element.

Fig. 3 is a perspective view of two of the said elements in one form of interengagement.

Fig. 4 shows four of the said elements in the same interengagement.

Fig. 5 is a completed ring shaped structure.

Figs. 6 and '7 are respectively end and side elevations of a structure formed of a plurality of the rings of Fig. 5 fastened together by external means.

Fig. 8 is a perspective view of one of my elements in a form which provides sidewise interengagement between elements.

Fig. 9 is a sectional view taken along the line 99 of Fig. 8.

Fig. 10 is a side elevation showing another mode of interengagement of elements similar to that shown in Figs. 1 and 2.

Fig. 11 is a plan view of an element combining the areas and functions of a plurality of the elements of Figs. 1 and 2.

Fig. 12 is a section view taken along the line l2--l2 of Fig. 11. v.

Fig. 13 is a longitudina1 sectional view of an element of laminated construction.

Referring particularly to Figs. 1 and 2, my elements in their preferred form have bodies I, terminating at one end in a tongue 2, less in width than the width of the body, and at the other end in a pair or tongues 3 and 4, which are interspaced, leaving what might be termed a groove 5, of a width to accommodate one of the tongues 2. The recessed end portions of the bodies such as the groove 5, or the portions cut away from the end of the member to form the tongue 2, are chamfered or beveled as at 6, the angularity of the beveled portion being the angularity or substantially the angularity, which the elements will have to each other in the completed polygonal structure. This angularity is in turn, of course,

determined by the number of sides of the polygon.

The several tongues extending beyond the body are grooved as at 1 and 8 (Fig. 2). This grooving leaves a shoulder I at each end of the body proper. The provision of these shoulders is an important aspect of my invention in contributing to the ultimate strength of the conduit in a way hereinafter set forth. It may be employed, whether or not the tongues extend beyond the surfaces of adjacent elements. and whether or not the tongues are provided with inwardly lacing shoulders as hereinafter described. The tongues, however, are preferably greater in length than the thickness of'the wooden elements, so that the grooving leaves shoulders ll near the ends of the tongues. The width of the grooves l and I is substantially the width of the chamfered portions 8 of the bodies. For appearance sake, the ends of the tongues 2. 3 and 4 may be chamfered or beveled as at It, II, but thisis not necessarv.

Elements such as have just been described are capable of interengagement as shown in Figs. 3 and 4. The interengagement is such, as will be evident, as to resist very strongly any tendency to increase the angularity between the elements. Aside from the purely elastic deformation of which my structures are capable, a forceable increase of the angularity between elements must result in the breaking of one or more of the tongues 2, 3 and 4. But in the completed structure; forces tending to increase the angularity between the elements occur only as a result of the action of various parts of the structure as arches. There are heavy compressive forces also which. when the pressures are substantially equalized all over the circumference of the structure, become the paramount forces. These forces are in part, resisted by the strength of the tongues 2, 3 and I; but it will be noted that the shoulders ll! of the adiacent elements abut each other. This feature gives to my structure a, greatly enhanced resistance to external compressive forces by reason of the actual abutment of the elements against each other, which not only increases the eiiectiveness of the strength of the tongues 2, 3 and l, by relieving them of considerable strain,

but also diminishes to a very useful degree, the

tendency 01' the interengagement of the tongues to produce longitudinal shearing stresses in the individual elements.

Fig. 5 shows a ring shaped structure for an octagonal culvert or conduit formed of the interengaged elements of Figs. 1 and 2. In forming the ring of Fig. 5, the elements are first engaged with each other in groups of four, as illustrated in that figure. Two such assemblies of four elements each may be opposed, and the interengagement of the ends of the assemblies with each other effected by pressure against the resiliency of the structure to'make the ring shown inFig. 5. This is easy to do, because the resiliency of the structure is such as readily to permit it; but it is not readily possible to assemble the structure. of Fig. 5 by engaging seven elements with each other, and then fitting in the last one. This can be done if the segments are thin enough, but it is not a preferred mode. The procedure which I have just outlined is the most convenient one to follow. The structure of Fig. 5 can be made by the simultaneous interengagement 01' four groups of two elements each, or of two groups of three elements each, and two single elements. The point is that the operation should be such in each instance as to permit interengagement by movement substantially in the direction of the chamfered planes 6. Where this is done the inherent resiliency of the structure permits ready interengagement.

Once the elements are interengaged as in Fig. 5, they are interlocked, and the structure is selfsustaining without the use of any extraneous fastening means.

A plurality of the structures of Fig. 5 may be made and may be Joined together to form a conduit by assembling them in side to side relationship, and may be held together by two or more battens l5 nailed in place, as shown in Figs. 6 and 7. But the individual elements may be made in such a way as to provide their own sidewise interengagement. As shown in Figs. 8 and 9, one side of each body I, may be provided with an outwardly extending rabbet or dovetail it, while the other side maybe provided with an inwardly extending rabbet or dovetail II. When such elements are assembled into a ring such as that shown in Fig. 5, additional assemblies such as that shown in Fig. 4, may be made and interlocked together, under such circumstances that the inwardly extending dovetail on one side of the assemblies of Fig. 4, interengages with the outwardly extending dovetail on one side of the ring of Fig. 5. This interengagement is illustrated in dotted lines in Fig. 9.

But my elements are capable of another type of interengagement such as not only to lock the elements together circumferentially ofthe culvert but also to lock them together axially of the culvert by means of the tongues.

The two tongues on one end of the elements of Figs. 1 and 2 are each preferably one-half the width of the single tongue on the other end of the elements. By reversing, end for end, alternate elements circumferentially of the culvert, it is possible to engage two of the narrow tongues (of axially adjacent elements) in the groove between the narrow tongues of a circumferentially adjacent element. At the other ends of these elements, the larger tongue of one element engages in the groove formed between the larger tongues of two elements, axially adjacent each other.

This is illustrated in Fig. 10, where the narrow tongue 4 of element l8 and the narrow tongue 3 of element 1!! lie side by side and are engaged in the groove between tongues 4, 3 of element 20. The tongue 2 of element l8 engages between the tongues 2 of elements 2| and 22. The result of this interengagement is to lock the culvert together axially, as will be clear, without the use of any other expedients such as the batten '5 or the rabbets l6, l1. Also it will be noted that the elements are staggered circumferentially of the culvert.

The culvert of Fig. 10 may conveniently be built up element by element. If the side portions of the narrow tongues 3, 4 of element 23 are slightly shaved oil orchamfered as exaggeratedly shown at 24, the tongue 4 may be inserted in the groove between the narrow tongues of element 25 alongside the tongue 3 of element l8. This is done while element 25 is in the plane of element It, but is cocked or tilted as shown. The cocking is permitted by the chamfering. When the interengagement of the narrow tongues has thus been effected, the element 23 is moved into parallelism with element ll, thus effecting interengagement of the tongue 2 of element 23 and the tongue 2 of element II. The culvert may thus progressively be formed to any length desired by the successive addition of elements. The abutment of shoulders l and II will be the same as that hereinabove described. The availability of the structure of Fig. as tunnel lining will be evident.,

Where wider lumber is available, it is not without thescope of my invention to make a unitary piece (Figs. 11 and 12) which is the equivalent of several of the individual elements of Figs. 1 and 2 in side-by-side relationship. Such composite structures may be interengagedas hereinabove described in connection with Figs. 3, 4 and 5. Where made of single pieces of lumber, the grain should run transversely, (i. e. fromtongued side to tongued side), in the member 26. v

Individual elements, or the composite structures of Fig. 11 may be made of plywood, if de-.

sired. The veneer layers should havetheir grains crossed, and at least the inner and outer layers should be adhered with an adhesive unaifected by moisture or the liquid which the conduit is to carry. Elements or composites may be cut from pre-formed plywood, as will be evident. But it is also possible, by die-cutting individual veneer layers to different appropriate sizes and shapes, to assemble them, properly coated with an adhesive (e. g. a synthetic resin), in a mould or die and consolidate and bind the layers together therein in initially the shape desired, or such a close approximation to that shape as to require very little cutting or trimming. Such an element or composite is illustrated in section in Fig. 13 at 21.

Modifications maybe made in my invention without departing from the spirit of it. Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. An element for forming conduits comprising an elongated body terminating at one end in at least one tongue of lesser width than the body and of a length at least equal to the thickness of the body, and at the other end-in at least one tongue of lesser width than the body and having a length at least equalto the thickness of the body, said tongues being so arranged on the body that they can come into crossing interengagement' with similar tongues .on similar elements ar-' ranged. circumferentially of a conduit, the ends of said body adjacent the bases of said tongues being formed at anangle to the axis of the body substantially equivalent to the angle of the aforesaid interengagement so that when said interengagement is effected it is an interenga'gement resistive to increase of the angle of the bodies to each other, the said tongues being relieved in such manner as to present an outwardly facing shoulder at each end of the said body, whereby when elements are interengaged as aforesaid their shoulders abut each other to resistjcompressive forces on the conduit.

2. The structure claimedinclaim 1 wherein said tongues are of such length that when interengaged with other tongues'theyextend beyond the outer surfaces of-the 'bodi I other tongues. the relieving aidg'tongueslas aforesaid terminating short-rof th 'enasgpr "said tongues whereby to leave inwardly facingshoulders near the ends of said tongues. p v

3. The structure claimed in claim 1 iii-which the said tongues are longer than'the effective thickness of another element withlthe tongues .:be.aring each of which the said tongues will interengage at the proper angularity to form a conduit of a polygonal cross section having more than four sides, and whereby the said tongues when so interengaged project beyond the outer surface of the said adjacent element, the relieving of said tongues terminating short of the ends of said tongues whereby to leave on said tongues unrelieved portions projecting beyond the outer surface of an adjacent element when interengagement is effected, and presenting an inwardly facing shoulder to engage said outer surface, whereby when elements are interengaged to form a conduit they will maintain an interlocked engagement.

4. A self-locking conduit ring having a polygonal cross section of more than four sides, said sides being formed of elements,'which elements are characterized by bodies, and at least one tongue at each end of said bodies, said tongues in said ring lying in interengagement, and said tongues being grooved in such manner that outwardly facing shoulders are provided on said bodies, the shoulder of one body being in abut-'- ment with the shoulder of another body in said ring, the said tongues being of such a length as to project beyond the outer surfaces of adjacent elements in said ring and being configured to provide inwardly facing shoulders abutting the outer surfaces of said adjacent elements whereby the elements in said ring are in interlocking interengagement.

5. A self-locking conduit ring having a polygonal cross section of more than four sides, said sides being formed of elements, which elements are characterized by bodies, and at least one tongue at each end of said bodies, said tongues in said ring lying in interengagement, and said tongues being grooved in such manner that outwardly facing shoulders are provided on said bodies, the shoulder of one body being in abutment with the shoulder of another body in said ring, the said tongues being of such a length as to project beyond the outer surfaces of adjacent elements in said ring and being configured to provide inwardly facing shoulders abutting the outer surfaces of said adjacent elements whereby the elements in said ring are in interlocking interengagement, said conduit being formed of a plurality of said rings in side by side relationship, and including means for fastening said rings together.

6. A self-locking conduit ring having a polygonal cross section of 'more than four sides, said sides being formed of elements, which elements are characterized by bodies, said tongues in said ring lying in interengagement, and said tongues being grooved in such manner that outwardly.

-gagement, said conduit being formed of a plurality of said. rings in side by side relationship, and including means for fastening .said rings together, said means comprising interengaging pro-- jections atthe sides of said bodies. 1

'7. The structure claimed in claim 1 wherein at one end of the body there is a single tongue centrally located and of substantially half the width of aid body, and at the other end there are two tongues, each of substantially half the width of the first mentioned tongue, and spacedfrom each other substantially the width of the first mentioned tongue.

8. The structure claimed in claim 1 wherein at one end of the body there is a single tongue centrall located and of substantially half the width of said body, and at the other end there are two tongues, each of substantially half the width of the first mentioned tongue, and spaced from each other substantially the width of the first mentioned tongue, and in which said tongues are long enough to extend beyond the outer surface of an adjacent element with the tongue or tongues of which said tongues are interengaged, and in which said tongues present inwardly facing shoulders adapted to abut the said outer surfaces.

9. The structure claimed in claim 1 wherein at one end of the body there is a single tongue centrally located and of substantially half the width of said body, and at the other end there are two tongues, each of substantially half the width of the first mentioned tongue, and spaced from each other substantially the width' of the first mentioned tongue, and in which said tongues are long enough to extend beyond the outer surface of an adjacent element with the tongue or tongues of which said tongues are interengaged, and in which said tongues present inwardly facing shoulders adapted to abut the said outer surfaces, and in which the said interspaced tongues are slightly chamfered at their outer sides so as to taper them.

10. In a conduit construction having a polygonal cross section with more than four sides, elements forming the sides thereof, said elements each having a body with a centrally located tongue at one end of substantially half the width of said body, and'a pair of tongues at the other end of substantially half the width of said first mentioned tongue and interspaced the width of said first mentioned tongue, the said elements being arranged circumferentially of said conduit in such a manner that a narrower tongue of each of two adjacent elements is engaged between the narrow tongues of a circumferentially adjacent element, and in which the wider tongue of each element is engaged between the wider tongues of two juxtaposed circumferentially adjacent elements.

11. In a conduit construction having a polygonal cross section with more than four sides, elements forming the sides thereof, said elements each having a body with a centrally located tongue at one end of substantially half the width of said body, and a pair of tongues at the other end of substantially half the width of said first mentioned tongue and interspaced the width of said first mentioned tongue, the said elements being arranged circumferentially of said conduit in such a manner that a narrower tongue of each of two adjacent elements is engaged between the narrow tongues of a circumferentially adjacent element, and in which the wider tongue of each element is engaged between the wider tongues of two juxtaposed circumferentially adjacent elements, and in which said several tongues are of such length as to project beyond the outer surfaces of adjacent elements, said tongues being grooved so that said bodies present outwardly facing shoulders which are in abutment in said conduit, and said tongues present inwardly directed shoulders which abut the outer surfaces of adjacent elements.

12. An element for a conduit construction, said construction being of polygonal cross section with more than four sides, said'element comprising a body elongated in the direction of the axis of the conduit, said body having a plurality of tongues at each side with intervening grooves, the bottoms of said grooves being cut to substantially the angularity of interengagement of said elements in forming said polygonal conduit, and said tongues being relieved in such manner as to provide an outwardly facing shoulder at each side of said body adaptedtoabut a similar shoulder on a similar body.

\ 13. The structure claimed in claim 12 wherein said several tongues are suificiently long to extendbeyond the outer surfaces of adjacent elements in said conduit, and in which said tongues are relieved in such a way as to present inwardly facing shoulders near the ends of said tongues adapted to engage the outer surfacesiof said adjacent elements.

14. The structure claimed in claim 1 wherein said element is made of plywood.

15. A method of assembling a conduit of polygonal cross section having more than foursides, which comprises providing elements each having a body with a tongue at one end centrally located, and of substantially half the width of said body, and a pair of tongues at the other, of substantially half the width of the first mentioned tongue, which comprises assembling said elements circumferentially in such manner that a pair of narrow tongues of two axially adjacent elements engage between the narrow tongues of a circumferentially adjacent element, and the wide tongue of an element engaged between the wide tongues of two circumferentially adjacent elements which are juxtaposed to each other, the said narrow tongues being chamfered at their outer surfaces, and building up the said conduit by inserting the narrow tongue of an element alongside the narrow tongue of another element (said elements being coplanar), between the nar row tongues of a circumferentially adjacent element, while the first mentioned element is in cocked position, and then moving said element until its wider tongue'engages the wider tongue of a circumferentially adjacent element while maintaining the coplanar relationship aforesaid.

16. A conduit ring having a polygonal crosssection of more than four sides, said sides being formed of elements which elements are characterized by bodies with at least one tongue at each end of each body, said tongues being of lesser width than said bodies and of at least the length of the thickness of said bodies, said tongues in said ring lying in crossing interengagement, the ends of said bodies adjacent the bases of said tongues lying aslant to the axes of said bodies, and the angularity of said bodies to each other in said ring being determined by the engagement of a tongue on one body with the slantwise disposed surface of the end of an adjacent body, said tongues being relieved in such manner that outwardly facing shoulders are provided on said bodies, the shoulder of one body being in abutment with the shoulder of another body in said ring.

GEORGE E. SHAFER. 

